PCPPI (sysbeep) crashes the kernel!

with the -current sources as for tonight, the sysbeep interface is
broken: pcppi and sysbeep interfaces lead to supervisor page faults,
either early while booting the kernel, or when a beep is supposed to sound.

That's not a very critical issue, but I'm curious to know if somebody
else noted that and what could cause such a crash in such a trivial driver.